1. Field of the Invention
The present invention relates to a planetarium picture-creating apparatus for projecting a picture such as a starry sky onto a dome screen on the basis of picture information, and a picture creating method thereof. More particularly the present invention relates to a planetarium picture-creating apparatus capable of representing movement in cosmic space as a pseudo space journey, and presenting activities such as take-offs from, and landings onto the surfaces of celestial bodies dramatically and a picture-creating method thereof.
Conventionally, a planetarium picture-projecting apparatus creates, projects and displays a picture of a starry sky on the basis of a manual operation including date-setting and viewpoint-setting. For example, if a pseudo space journey is represented, a process of changing the positions of celestial bodies along with changes of viewpoint is carried out (see, for example, JP Unexamined Patent Publication No.2004-361584). A product “super-MEDIAGLOBE” has a take-off and landing function (see the back face of the cover sheet of the monthly publication “HOSHI NAVI June 2005, edited and published by KABUSHIKI-KAISHA ASTROART and sold by KABUSHIKI KAISHA ASKEE). This is a function capable of facilitating the projection of situations in which movement takes places through a series of motions from the surface of a celestial body to airspace enabling a commanding view of that celestial body. And also, from airspace to the surface of the celestial body.
When a change of viewpoint is represented, for example, when a viewpoint approaches a celestial body or retreats from the celestial body, the size of an object displayed that expresses the shape of the celestial body changes commensurately with a distance from the viewpoint. In general terms, a surface pattern of a celestial body is prepared as a static image, a texture. So, the celestial body is expressed by pasting the texture onto the area where the object is displayed. Thus, during processing in which the size of an object changes, the static image is pasted in a state of enlargement or reduction with changes of the size of the object.
In animation contents of a pseudo space journey operated on a personal computer, a plurality of picture information is generally prepared that corresponds of movement between a first viewpoint and a second viewpoint. One of these pictures is expressed in an enlarged form corresponding to movement of the viewpoint. It is changed into the subsequent picture at a predetermined timing, and the picture in turn is expressed in an enlarged form. Consequently, animation contents corresponding to movement of a viewpoint from airspace some several tens of meters above ground level up to an altitude of an artificial satellite, or contents such as reproducing movement from the surface of the ground to cosmic space, have been achieved.
However, in the conventional planetarium picture-creating apparatus described above, only one texture has been prepared for each celestial body. Thus, if it is intended to express a condition in which a viewpoint is very close to the surface of the celestial body, an extremely enlarged image of the texture is displayed. For example, if travel from the surface of the earth into cosmic space by rocket is represented, an extremely enlarged image of the earth having a low degree of resolution is displayed in a situation in which the viewpoint is very close to the surface of the earth. Accordingly, a problem arises that such a picture is deficient in terms of a sense of realism and a high quality of presentation cannot be achieved.
Further, in the animation contents of a personal computer, only the surface texture of the earth is reproduced and conditions in cosmic space around the earth cannot be reproduced at the same time. Even if an animation picture is prepared for conditions in which cosmic space around the surface texture of the earth in advance, displayed pictures are limited to that from predetermined time on and from predetermined viewpoints. Thus, for these reasons, it cannot be expressed a condition of the sky in which bodies such as the sun, moon, planets, satellites, fixed stars and the milky way change, and a condition of the surface of the earth which is retreating at the same time.